Polyarylene sulfides are high-performance polymers that may withstand high thermal, chemical, and mechanical stresses and are beneficially utilized in a wide variety of applications. Polyarylene sulfides are generally formed via polymerization of p-dichlorobenzene with an alkali metal sulfide or an alkali metal hydrosulfide, forming polymers that include chlorine at the terminal groups. With low halogen-content polymeric materials becoming increasingly desired due to environmental concerns, attempts have been made to produce low chlorine content polyarylene sulfide compositions. In general, this has involved utilizing higher molecular weight polymers in the compositions, as higher molecular weight polyarylene sulfides will include fewer terminal groups and hence have lower chlorine content.
Unfortunately, high molecular weight polyarylene sulfides have high melt viscosity, and this presents processibility issues that may complicate formation techniques. This problem may be aggravated with the inclusion in a polyarylene sulfide composition of fillers that may improve desirable characteristics of the formed composites but also further increase melt viscosity of the composition.
The utilization of lower molecular weight polyarylene sulfides may improve processibility of a composition, but the high chlorine content is still a problem, and the inclusion of additives to improve physical characteristics of a composition may lead back to processibility problems, as the add-in level for additives may be quite high in order that the composition including the low molecular weight polyarylene sulfide exhibit the desired physical characteristics.
What are needed in the art are melt processed polyarylene sulfide compositions that have a relatively low melt viscosity for good processibility while still providing desirable physical characteristics and low chlorine content. In addition, what are needed are facile, straightforward methods for forming the melt processed polyarylene sulfide compositions that do not require complicated or extensive processing steps.